Filter means and method of making same



F'ehzo, 1940. A. E. SCHAAF Erm- 2,190,886

I3 l2 a,

Pfat'ent'edjFeb. 20,194.0, i

jum'rsos'lrsrss. PATENT. OFFICE- A 'gzgisosss *l t albert E.; schaar, Falls,v VM.'

Walton, lCleveland Heights, 'and Clarence I.

Glanzer, Lakewood,l Ohio, assignors to Airf- V Male -Corporation, Cleveland, Ohio, a corporation o f Y 'Appucstmn June 7, 1939, serial No. 211,835

4 claims.r (ci. iss- 11) 'i This invention relates to improvements in lter means and a method of making. the same.

An object of the present invention is to provide` a filter element of screen material wherein special attention is paid to masking4 the raw edges of the screen. It will be appreciated by -those who havehndle'd this type of lter ele-` ment that the raw edges of the screen ,make these elements very difficult to handle for processing purposes or for assembly in proper mountings or for a rolling operation to make an annular nlter element.

Another object of the present invention is to provide a novel screen element of several thicknesses of screen material wherein certain ofthe layers have nesting corrugations and other layers are held apart by non-nesting cori'ugations.4

g Another object of the present invention is -to provide a novel method for constructing a filter element of the type above ydescribed as will more clearly appear from the accompanying drawing and description.

- In the drawing, Fig. 1 is a plan view showing the first step in forming apiece of screen material into the novel filter element; Fig. 2 shows a portion of the folded strip of Fig. 1 corrugated' along parallel lines; Fig. 3 isanv enlarged fragmental sectional view taken in the position of the line 3 3 of Fig. 2; Fig. 4'is a plan view of a strip similar to Fig. 2 folded over upon itself lengthwise and illustrating the crossing of the corrugations between adjacentstrips of double thickness; Fig. 5 is an enlarged fragmental" sectional view taken along the line 5-5 of Fig. 4; while Fig. 6 is an end view illustrating how the strip of Fig. 4 may be rolled to form an annular filter element.

This invention 4is in the nature of an improvement over our copending application Serial No.

strip other thsn'normn as indicated in Fig; 2 where the corrugated strip -is marked I2a. As

- more clearly indicated in Fig. 3 the result at this point is a. strip of double thickness having nesting corrugations I3a and lib. L,

The next step V.is to fold the strip I2a endwise along one or more lines I5 which extend normal to the longitudinal side edges of the strip l2a. Thus the portions l2b are'folded over on top of the lower portion I2a and as shown in Fig. 4 this places the corrugations I5 of theupper layer at an angle to the corrugations i3 in the lower layer' so that each double thickness is separated from the other because of the non-nesting corrugations.

The above described eilect of non-nesting layers of screen is obtainedby a single fold I4 but preferably I provide such a fold at each end of the strip as indicated in Fig. 4 s o as to leave no raw edges at the ends of the strip. It will be noted that in the form of Fig.' 4 there are no raw edges of the screen either at vthe sides or ends f' of the strip.

To more' clearly indicate the character of the strip of Fig. 4 having four layers of wire screen,

we have shown an enlarged detail in Fig. 5. Here the layers lia and I3b have nesting corrugations as shown in Fig. 3. 'I'he layer l2b has the nesting corrugations here Vindicated as I5a and l5b for clearness of description although it will be understood that these are the lsaine corrugations as in the layer l2a and simply folded over upon the same. In Fig. 5 then we have on one side of ofthe strip the nesting layers I'3a and I3b and on the other side the nesting layers 15a and I5b,

but the two layers are separated in a non-nesting manner, that is to say, the corrugations l3a and Ilia do not nest because they lie at an angle one to the other as indicated in Fig; 4.

133,428, led March 27, 1937. The strip of Fig. 4 may be utilized in any de- 40 Our improved filter element will be best undersired fashion either straight,V curved or otherstood by a description of the successive steps necwise folded, but a common manner of using the essary or desirable lin -forming it. In Fig.- 1 Same is to-roll it into' an annular filter element, we haveshown a piece lll substantially rectangua partial view of lwhich is shown in Fig. 6. For lar in shape of a flat wire screen material. 'Ihis this purpose the ends I6 of the layer I2b in Fig. 45

is run through forming rolls which fold the side edge portions llla'and lllb inwardly upon the intermediate portion 4lllc of thepiece of screen materlal preferably so that theedges meet as indicated at ll giving an elongated strip of screen material of double thickness. Such a strip appears at the left end of Fig. 1 and is marked I2. This double strip is then run through a pair of crimping rolls to provide parallel corrugations Il extending at an angle to the side edges of the .`forxn ofv Fig. 6 then the adjacent layers, as for instance those contiguous at Il and I8. are nonnesting as to the corrugationsbecause in the i' Cil automatic machinery. Also the non-nesting relationship of adjacent layers indicated in Fig. 4 is formed much more conveniently by the short cross folds I4 rather than by the extremely long longitudinally extending folds utilized to provide this non-nesting relationship in the device of the copending application. Furthermore the article here formed gives a screen of greater density because of the crimping of the double layers, and the masking of all of the raw edges of the wire screen material is very advantageous in the handling of the finished product and in the rolling of the strip of Fig. 4 to the annular form of Fig. 6.

What We claim is:

1. A lter unit comprising an elongated strip of screen material having its side edges folded along parallel lines inwardly over a central portion of the strip forming a strip of double thickness, said double strip having parallel nesting corrugations at an angle other than normal to the side edges of the strip, and said strip being bent transversely to fold one portion of said double strip lengthwise over another portion thereof, whereby the last named folded over portion does not nest on the underlying portion because of crossing corrugations.

2. A filter unit comprising an elongated strip of screen material having its side edges folded along parallel lines inwardly over a central portion of the strip in such a manner that the said side edges lie between the edges of the folded strip and forming a strip of double thickness,

said double strip having parallel nesting corrugations at an angle other than normal to the side edges of the strip, said double strip having its end edges folded along. lines normal to the side sides or ends of said unit.

3. The method of,making a. filter element comprising folding two side portions of a rectangular piece of screen material along lines parallel to opposite sides of said rectangle lnwardly upon a central portion of the piece in a manner to provide an elongated strip of double thickness, corrugating said double strip along parallel lines other than normal to the side edges of said double strip, and folding said double strip endwise along a linenormal to its side edges, whereby'to form a strip of four screen layers wherein two pairs of layers have nesting corrugations andthe pairs are separated from each other by non-nesting corrugatins.

4. The method of making a filter element comprising folding two side portions of a rectangular piece of screen material along lines parallel to opposite sides of said rectangle inwardly upon a central portion of the piece in a manner to provide an elongated strip of double thickness, corrugating said double strip along parallel lines other than normal to the side edges of said double strip, and folding each end of said double strip endwise over upon the central portion of said double strip, said last named folds being along lines normal to the side edges of said double strip, whereby to form a strip of four screen layers wherein two pairs of layers have nesting corrugations-and the pairs are held apart by non-nesting corrugations and there are no raw edges at the sides or ends of said unit so that it is easily handled as for instance for rolling into an annular element.

ALBERT E. SCI-IAAF.

GEORGE M. WALTON.

CLARENCE J. GLANZER.. 

